Introduction
On airplanes, modular electronic devices are mounted on fixed shelves. The electronic connections between the modular electronic devices are made with interconnecting wire bundles. It has been shown that a printed wiring board (PWB) in place of the interconnecting wire bundles would save weight, space, and cost.
However, the airplane industry has a history of introducing modifications to electrical wiring in the field. Whereas changes to wire bundles can be made directly in the airplane, making changes (cuts and jumpers) to a PWB cannot. Therefore, PWBs have not replaced wire bundles.
Background
Traditionally, the connections between modular electronic devices on commercial airplanes have been made with wire bundles. It has been shown that in cases where a series of modular electronic devices are mounted on fixed shelves, a printed wiring board in place of the interconnecting wire bundles would save weight, save space and cost less to produce.
The airplane industry has a history of introducing modifications to electrical wiring in the field. Airlines perceive changes to printed wiring boards using conventional methods as an obstacle to their use. The confines of the electronics bay of a commercial airplane do not allow the kind of precision work needed for making PWB modifications. The soldering irons needed for adding jumpers is considered hazardous in the flightline environment where fuel vapors are sometimes present.
Printed wiring boards in combination with wire wrap technology has been proposed as an alternative to pure printed circuits. While this solution offered a good way of adding jumpers, it did not offer practical advantages for making cuts. Wire wrap has also been viewed with disfavor due to its susceptibility to foreign object contamination.
Problem Solved by the Present Invention
Once a device with a printed wiring board is designed and built, it is difficult or impossible to change the connectivity of the wiring board in the field in the end product. Making changes to printed wiring boards has traditionally been done by adding "cuts" and "jumpers" to the board. The cut and jumper work is typically only performed in special repair facilities by specially trained technicians using specialized tools. The "cuts" are made by drilling or scraping away the copper trace where the connection is no longer desired. The operation often requires precision in locating the proper trace. The "jumpers" are added by soldering the ends of an insulated wire to the points where a new connection is desired.
The present invention allows changes in connectivity to be introduced to a device using only the tools, skills and materials that would be familiar to a mechanic with a background working with wire bundles. Further, the modifications can be done where the printed wiring board is installed instead of a repair facility.